Porosity Content Research Articles

Corrosion and Erosion Wear Behaviors of HVOF-Sprayed Fe-Based Amorphous Coatings on Dissolvable Mg-RE Alloy Substrates.

To suppress the corrosion and erosion wear of dissolvable magnesium alloy ball seats in wellbores, Fe-based amorphous coatings were deposited on dissolvable Mg-RE alloy substrates, and their microstructure, corrosion behavior, and erosion wear behavior were studied. The thickness of Fe-based amorphous coatings on dissolvable Mg-RE alloy substrates can reach 1000 μm without any cracks, and their porosity and amorphous contents are 0.79% and 86.8%, respectively. Although chloride ions will damage the compactness and protective efficacy of passive films, Fe-based amorphous coatings still maintain low corrosion current density (3.31 μA/cm2) and high pitting potential (1 VSCE) in 20 wt% KCl solution. Due to their higher hardness, the erosion wear resistance of Fe-based amorphous coatings is about 4.16 times higher than that of dissolvable Mg-RE alloy substrates when the impact angle is 30°. Moreover, the erosion rates of Fe-based amorphous coatings exhibit a nonlinear relationship with the impact angle, and the erosion rate reaches the highest value when the impact angle is 60°. The erosion wear mechanisms of Fe-based AMCs vary with the impact angles, including cutting, delamination, splat fracture, and deformation wear. This work can provide effective guidance for the corrosion and wear protection of plugging tools made from dissolvable magnesium alloy.

Improving coarse-textured mineral soils with pulp and paper mill sludges: Functional considerations at laboratory scale

Building up the organic matter content of coarse-textured soils with organic amendments seeks to ameliorate the productivity of these soils, which is limited by plant available water and nutrient supply. Wood fibre-based sludges from the pulp and paper industry have potential for soil conditioning. In this study, the effects of three different pulp and paper mill sludges at application rates of 10 and 20 vol-% on water retention, respiration, and nitrogen (N) dynamics were examined in a series of laboratory studies using coarse field soils. Water retention curves comprising 13 matric potentials revealed that the amendments increased total soil porosity and volumetric water content at matric potentials corresponding to macro- and mesopores size range with pore diameters of >30 μm and 30–0.2 μm, respectively. Volumetric water content at field capacity increased by c. 10–30%, depending on the type (fresh, lime-stabilised and fibre sludge) and application rate of the amendment, with no marked change in the water content at the permanent wilting point. This was reflected as a mean increase of 1.9–3.3 mm in the plant available water content relative to the non-amended soils (17 mm), which corresponds to 19–33 m3 per hectare. At most, an increase of 5.5 mm (55 m3 ha−1) in plant available water was achieved by the fibre sludge amendment at an application rate of 20 vol-%. During a 60-day laboratory incubation, c. 30–40% of the carbon (C) added to soil in the sludge materials was respired as carbon dioxide. Additional N accelerated decomposition without increasing total respired C. Decomposition of the amendments in the soil led to a net N immobilisation of roughly 5–10 mg min-N g−1 added C, which occurred mainly during the first two weeks after soil incorporation. Overall, pulp and paper mill sludge amendments may serve to alleviate water shortages during drought in coarse-textured soils, but may generate a transient plant-microbe competition in N uptake.

Influence of the interlayer temperature on structure and properties of CMT wire arc additive manufactured NiTi structures

A potential method for producing intricate Shape Memory Alloy (SMA) structures for uses like actuators and vibration dampers is wire arc additive manufacturing (WAAM). However, excessive heat build-up during the multi-layer deposition procedure in WAAM can result in process instability and departures from the intended mechanical qualities and dimensions. To address these problems, the interlayer temperature was optimized for printing on NiTi walls in this work. Without interlayer temperature control (WITC), 200 °C, and 400 °C were used to create three samples in order to study the impacts on the porosity level, morphology, and mechanical characteristics of the NiTi walls generated by WAAM. The Shape memory behavior of the manufactured NiTi walls was further examined through shape recovery investigations utilizing hot plate actuation. The findings demonstrated that regulating the interlayer temperature below 300 °C, preferably at 200 °C, enhanced the mechanical characteristics, decreased the porosity content, and enhanced the microstructure of the NiTi walls. The development and improvement of WAAM techniques for the manufacture of premium NiTi SMA components can benefit greatly from these findings.

Weed infestation and productivity of wheat crop sown in various cropping systems under conventional and conservation tillage.

Climate change, pest infestation, and soil degradation are significantly reducing wheat (Triticum aestivum L.) yield. Wheat is cultivated in rice-wheat and cotton-wheat cropping systems and escalating global population is exerting substantial pressure on the efficiency of these systems. Conservation tillage and crop rotation could help in lowering soil degradation and pest infestation, and improving wheat yield. This three-year study evaluated soil properties, weed infestation and wheat yield under various tillage and cropping systems. Six different cropping systems, i.e., cotton-wheat, sorghum-wheat, mungbean-wheat, rice-wheat, sunflower-wheat, and fallow-wheat (control) and three tillage systems, i.e., conventional tillage (CT), zero-tillage (ZT) and minimum tillage (MT) were included in the study. The individual and interactive effects of tillage and cropping systems significantly affected soil properties, weed infestation and yield of wheat crop. Overall, CT resulted in lower soil bulk density and higher porosity, while ZT behaved oppositely at all locations in this regard. Similarly, mungbean-wheat cropping system resulted in lower bulk density and higher porosity and nitrogen (N) contents, while fallow-wheat cropping system resulted in higher bulk density, and lower soil porosity and N contents. Similarly, ZT and CT resulted in higher and lower weed infestation, respectively. Likewise, lower and higher weed density and biomass were recorded in wheat-sorghum and wheat-fallow cropping systems, respectively at all locations. In the same way higher number of productive tillers, number of grains per spike, 1000-grain weight, grain yield, and economic returns of wheat crop were recorded for CT, whereas ZT resulted in lower values of these traits. Regarding interactions, wheat-mungbean cropping system with CT resulted in lower bulk density and higher porosity and N contents, whereas wheat-fallow system with ZT behaved oppositely at all locations in this regard. Similarly, higher and lower values for yield-related traits and economic returns of wheat crop were noted for mungbean-wheat cropping system under CT and fallow-wheat and sorghum-wheat cropping systems under ZT, respectively. It is concluded that the mungbean-wheat cropping system improved wheat productivity and soil health and sorghum-wheat cropping system could lower weed infestation. Therefore, these cropping systems can be practiced to lower weed infestation and improve wheat yield and economic returns.

Nonlinear Ultrasonic Imaging for Porosity Evaluation.

The influence of porosity on the mechanical behaviour of composite laminates represents a complex problem that involves many variables. Therefore, the evaluation of the type and volume content of porosity in a composite specimen is important for quality control and for predicting material behaviour during service. A suitable way to evaluate the porosity content in composites is by using nonlinear ultrasonics because of their sensitivity to small cracks. The main objective of this research work is to present an imaging method for the porosity field in composites. Two nonlinear ultrasound techniques are proposed using backscattered signals acquired by a phased array system. The first method was based on the amplitude of the half-harmonic frequency components generated by microbubble reflections, while the second one involved the frequency derivative of the attenuation coefficient, which is proportional to the porosity content in the specimen. Two composite samples with induced porosity were considered in the experimental tests, and the results showed the high accuracy of both methods with respect to a classic C-scan baseline. The attenuation coefficient results showed high accuracy in defining bubble shapes in comparison with the half-harmonic technique when surface effects were neglected.

Covalent triazine polymer derived porous carbon with high porosity and nitrogen content for bifunctional oxygen catalysis in zinc–air battery

Nitrogen-doped porous carbon possesses widespread applications in energy-related fields due to its unique properties. However, preparation of porous carbon (specific surface area > 3000 m2 g–1) with high nitrogen content (> 10 wt%) remains great challenges because of high synthesis temperature. Herein, a covalent triazine polymer was innovatively designed by cyclotrimerization of tetracyanoethylene, and used to produce the high nitrogen-doped porous carbon. The as-prepared porous carbon (HNPC-900) possesses a high nitrogen content (14.2 wt%) and large specific surface area (3210 m2 g–1). When HNPC-900 was applied as the air-cathode for zinc–air batteries, it shows a high specific capacity (797 mAh gzn–1) and stable rechargeability (more than 380 h over 960 cycles at 5 mA cm–2), outperforming the cathode composed of RuO2 and 20 wt% Pt/C. This ingenious design provides a feasible strategy to prepare high nitrogen-doped porous carbon, giving extensive application prospects of porous carbon for catalysis and energy storage fields.

The ceria – Germania solid oxide hydrogen storage hollow porous nanoparticles

The combination of high specific surface area and high porosity content as diffusion routes for adsorption/desorption in monodispersed solid state mixed oxide ceramic nanosized hollow porous particles enabled high hydrogen storage capacity with promising platform for controlled gas molecules delivery. The synthesized thin-walled nanoparticles were characterized for crystallinity, bond structure, morphology, and surface activity/adsorption profiles. The optimum molar ratio mixture of equal parts ceria and germania in hollow porous nanoparticles stored up to 7.8 wt% with specific surface area near 6100 m2/g and about 2 cm3/g volume content of 2.9 Å pores. The maximum discharge capacity of ∼5600 mAh/g after 12 cycles of this mesoporous structure provided a considerable storage performance and reversibility at ambient conditions. The structure dependency of storage was attributed to structural characteristics in CeO4 - GeO6 polyhedras and alterations between oxidation states in ceria.

Characteristics and Geological Impact Factors of Coalbed Methane Production in the Taiyuan Formation of the Gujiao Block

The coalbed methane resources of the Gujiao Block are abundant, and the exploration degree is high. The gas production and water production of different CBM (coalbed methane) wells vary greatly. The average gas production of CBM wells in the study area is mostly less than 1000 m3/d, while the average water production is mostly less than 5 m3/d. The gas production of CBM wells near the core of the Malan syncline is relatively high. A series of large faults exist in the central and eastern parts of the study area, and CBM wells nearby produce more water but less gas. The salinity of water discharged from CBM wells ranges from 810.34 to 3115.48 mg/L, which is consistent with the trend of a gradual increase from north to south. The gas content distribution follows this same gradually increasing north to south trend. Coal thickness and buried depth have little effect on gas production, but have some effects on water production. The endogenous fracture system in the coal reservoir is extremely developed and the porosity and permeability of the reservoirs are low, which is not conducive to the migration and recovery of coalbed methane. The adsorption capacity of the coal sample is strong. However, the continuous uplift and denudation of the stratum from the middle Yanshanian to the Himalayan region are not conducive to the preservation and enrichment of coalbed methane. In addition, a series of large faults exist in this area, and the coal structures are broken. A large amount of coalbed methane is continually being released. Generally, structural and hydrological conditions affect the porosity, permeability, and gas content of coal reservoirs, thereby affecting the productivity of coalbed methane wells. The comprehensive analysis shows that the Xingjiashe well field in the southern part of the study area is a favorable area for CBM exploration and development.

Estimating soil water retention curves from thermal conductivity measurements: A percolation-based effective-medium approximation

A soil water retention curve (SWRC) describes the relationship between soil water content (θ) and suction (h, also the absolute value of pressure head). Earlier work indicated that correlations existed between the percolation-based effective medium approximation (P-EMA) thermal conductivity (λ) model parameters and soil hydraulic properties. In this study, the critical water content (θc) of the P-EMA model was related to the pore size distribution parameter (m) of the van Genuchten model, water content at the inflection point of a SWRC (θi) and hydraulic continuity water content (θhc). And a pedo-transfer function was established to estimate the van Genuchten model parameter α from soil properties and P-EMA parameters. Based on these relationships, three approaches were developed to estimate the van Genuchten models parameters from λ(θ) measurements, porosity, sand and clay contents. The three approaches were then validated on six independent soils, and results showed that all of the approaches estimated θ well at selected h values, with the average root mean square errors from 0.025 to 0.029 cm3 cm−3, the average mean relative absolute errors ranging from 0.111 to 0.157, and the average Akaike Information Criterion from −18.3 to −16.2. Two new approaches outperformed the original Fu et al approach but with fewer input parameters (no need for organic carbon content), thus also facilitating their broader application.

Spatiotemporal variation in soil methane uptake in a cool-temperate immature deciduous forest

Atmospheric methane (CH4) concentration has been increasing recently, contributing to global warming. As natural sinks, forest soils are expected to mitigate the atmospheric CH4 rise. However, it had been difficult to measure soil CH4 flux continuously and accurately because of the limited stability and precision of CH4 analyzers in the field. In this study, we measured hourly CH4 flux with plant roots (Root) and without roots (Trench) during the growing season in a regenerating deciduous forest using an automated chamber system with an up-to-date analyzer. Combined with a Random Forest (RF) approach, we studied the spatiotemporal variation and control of soil CH4 uptake rates. The results showed that the soil was a CH4 sink throughout the experimental period, and the existence of roots significantly enhanced CH4 uptake, mainly through improving soil aeration. The CH4 uptake rate varied seasonally according to the variations in soil gaseous diffusion caused by soil moisture and temperature differences. In addition, soil CH4 uptake showed a significant spatial variation, mainly resulting from spatial difference in soil porosity, soil carbon and nitrogen contents, and fine root biomass. The RF models showed high performance in soil CH4 flux prediction using the soil O2 diffusion coefficient and soil temperature as explanatory variables. The performance of RF models using ordinary variables of soil water content or water-filled pore space (WFPS) was equal to or slightly better than that of models using the diffusion coefficient. The higher importance of ambient CH4 concentration in Trench chambers indicates an increase in soil CH4 uptake at higher CH4 concentrations, which is predicted in the future. Although there are limitations, we believe that a machine learning approach, such as RF, using a large amount of continuous data with high temporal resolution, has great potential for investigating the dynamic variation in soil CH4 flux.

Assessment of soil health in uncontrolled grazing areas in the Administrative Post of Luro, Lautem, East Timor

Abstract. Costa DD. 2023. Assessment of soil health in uncontrolled grazing areas in the Administrative Post of Luro, Lautem, East Timor. Intl J Trop Drylands 7: 46-54. Uncontrolled grazing practices have been judged as the main cause of soil degradation in grassland areas. This study was conducted to provide baseline information on soil health in uncontrolled grazing areas in the administrative post of Luro, municipality of Lautem, East Timor (Timor Leste). Furthermore, 40 soil samples were collected from eight uncontrolled grazing areas using the core method; five points sampling per each site (four in corners and one in in the center) sampling points distances were 100 to 150 m apart, and each point represented three different soil layers (0-5 cm, 5-10 cm, and 10-20 cm). All soil samples were transported to the laboratory of the Faculty of Agriculture, Universidade Nacional Timor Lororsae, East Timor. Samples preparation and analysis followed the procedure and guidelines of McKenzie et al. (2002) and Liu et al. (2019) for physical properties, while Soil Organic Matter (SOM) analysis used Loss-On-Ignition (LOI) adopted from Nakhli et al. (2019). In addition, all soil chemical properties were analyzed using Kjeldhal and Bray-1 method following the soil analysis guidelines of JICA (2014). The study showed that soil physical properties in the uncontrolled grazing areas in Luro are characterized by high bulk density, poor porosity, and low organic matter content. Furthermore, soil pH remains neutral in areas where uncontrolled grazing is practiced but with very low nitrogen and potassium levels. In contrast, phosphorus is very high in the Cotamuto and Lakawa but very low in the Afabubo areas. Furthermore, low literacy levels and livelihoods are key socioeconomic factors that directly influence uncontrolled grazing practices. Hence, promoting sustainable grazing methods among communities towards raising livestock for their livelihood is recommended.

Estimated versus field measured soil gas radon concentration and soil gas permeability

Prediction of areas with elevated natural radiation is fundamental for the prevention of human exposure. Soil gas radon activity concentration and soil gas permeability are predictive parameters for the radon potential, which has great importance in areas where future urban development is planned. In this study, the soil gas radon equilibrium concentration (C∞) and soil gas permeability (K) were estimated through the application of theoretical and empirical models found in the literature. These models apply soil properties as input parameters. Using already existing soil parameters to predict the radon potential of an area would be useful in avoiding direct field measurements. Therefore, in this study, we examined whether the estimated soil gas radon activity concentration and soil gas permeability values match the values measured in the field. The soil gas radon activity concentration estimated by two theoretical models is about 50% of the measured value in the studied area. This underestimation can be attributed to the assumption that the radon activity concentration measured in the field depends only on soil parameters and the models do not take into account the underlying bedrock. Additionally, these models neglect the radon transport by advection and consider only the radon availability and migration in homogeneous media. Furthermore, they do not count certain characteristics of the soil that can be relevant, e.g. organic matter and clay content in the soil. To investigate more in detail such soil characteristics, seven samples located roughly along the slope, were selected to determine the soil chemical composition by ICP-MS. Evaluating the physical and chemical properties of the soil, it was found that the sampling sites with pH < 8 (low calcium content) the preferential adsorption was a dominant process. This causes radium enrichment in organic matter and clay, which directly influence the soil gas radon activity concentration. At pH > 8, radium is no longer preferentially adsorbed on organic matter but continues to be adsorbed on clays albeit this process is weak because radium competes with calcium cations. Also, there are other factors that may affect radon emanation in soil such as radium concentration and distribution, porosity and water content. In contrast, empirical model of soil gas permeability overestimates the measured value in the study area by an order of magnitude. A new model was made by modifying the previously proposed one, which can be used as a guide for the estimation of the median value of soil gas permeability in granitic areas, but not as an accurate predictor due to the lack of correlation between the estimated and measured values.

Facile preparation of S, O-codoped carbon materials from wasted pulping liquid for supercapacitors

Hierarchical porous carbon S, O-doped is prepared by a facile and green way using industrial red pulping liquid as precursor and mild potassium chloride as initial templates to initiate templates regeneration. Replacement reactions occurs between potassium chloride and sodium atoms on precursors to form a more stable sodium chloride template, which is used to adjust pore structure during the etching process. Rich phenolic structures and sulfur groups in precursor result in the prepared porous carbon with many advantages for supercapacitors, including excellent specific surface area (1873.6 m2 g−1), high graphitization degree, hierarchical porosity and rich heteroatom content. The specific capacitance of fabricated samples can successfully achieve 386.9 F g−1. In addition, assembled energy storage device shows a remarkable energy density 8.6 Wh kg−1 at 21 kW kg−1 power density, and after 10,000 cycles, specific capacitance retention rate can be 86.4%. The superior electrochemical performances demonstrate a great potential candidate of industrial wastes for energy storage devices with excellent properties.

Effects of moisture content and porosity on the thermal conductivity and volumetric specific heat capacity of pharmaceutical powders

Thermal conductivity and specific heat capacity are two important parameters for the drying process of pharmaceutical materials during methods such as wet granulation that can be observed in the overall tablet manufacturing process. In this study, a transient line heat source method was used for the first time to determine the thermal conductivity and volumetric specific heat capacity of common pharmaceutical components and binary mixtures, with moisture content ranging from 0 % to 30 % w.b and active ingredient loading between 0 % and 50 % by weight. A three-parameter least squares regression model relating the thermal properties to moisture content and porosity was evaluated at a 95 % confidence interval, with R2 values ranging from 0.832 to 0.997. Relationships were established between thermal conductivity, volumetric specific heat capacity, porosity, and moisture content for pharmaceutical ingredients including acetaminophen, microcrystalline cellulose, and lactose monohydrate.

Aloe vera-Based Polymeric Network: A Promising Approach for Sustained Drug Delivery, Development, Characterization, and In Vitro Evaluation

The present study was conducted to fabricate and characterize mucilage-based polymeric networks of Aloe vera for controlled drug release. Aloe vera mucilage was used to develop a polymeric network via the free-radical polymerization method using potassium persulphate as the initiator, N′ N′-Methylene bisacrylamide as the crosslinker, and acrylamide as the monomer. Using varying concentrations of Aloe vera mucilage, crosslinker, and monomer, we developed different formulations. Swelling studies were conducted at pH 1.2 and 7.4. Concentrations of polymer, monomer, and crosslinker were optimized as a function of swelling. Porosity and gel content were calculated for all samples. FTIR, SEM, XRD, TGA, and DSC studies were conducted for the characterization of polymeric networks. Thiocolchicoside was used as a model drug to study the in vitro release in acidic and alkaline pH. Various kinetics models were applied by using a DD solver. Increasing content of monomer and crosslinker swelling, porosity, and drug release decreased while gel content increased. An increase in Aloe vera mucilage concentration promotes swelling, porosity, and drug release of the polymeric network but decreases gel content. The FTIR study confirmed the formation of crosslinked networks. SEM indicated that the polymeric network had a porous structure. DSC and XRD studies indicated the entrapment of drugs inside the polymeric networks in amorphous form. The analytical method was validated according to ICH guidelines in terms of linearity, range, LOD, LOQ, accuracy, precision, and robustness. Analysis of drug release mechanism revealed Fickian behavior of all formulations. All these results indicated that the M1 formulation was considered to be the best polymeric network formulation in terms of sustaining drug release patterns.

Strength enhancement of cement-based stabilized clays via vacuum-assisted filtration

The performance of the cement-based stabilized clay (CBSC), a kind of typical composite, is controlled by the homogeneity and interactions among the hydration products of the cementitious agents, clay minerals and water. For the shallow lowland ground by hydraulic filling or natural deposition with very high-water content, more cementitious agent was required to realize the designed strength when block solidification, where a higher water content should improve the feasibility and homogeneity but decrease its strength. To overcome this contradiction, a vacuum-assisted filtration technique used in sludge and concrete treatment was extended to remove excessive water within the CBSC for strength enhancement. Experiments including the laboratory and pilot project were conducted to study the efficiency of the filtration method by investigating tailing water volume, strength and microstructure of the CBSC. Results reveal that applying the filtration method can effectively discharge the free water from the CBSC within the initial 12 hrs’ hydration of the cementitious additives, with a reduction in water content by 5.8–24.7 %, accompanied by an increase in the 28-day’s strength by more than 1.7 and 1.6 times in the laboratory and field respectively. Microstructural and chemical analyses also reveal that the strength improvement originates from the enhanced mixing homogeneity facilitated by higher water content and subsequent filtration for cementation development. After the auxiliary filtration process, both the total porosity and water content decrease, and the large pores are transformed into smaller ones.

Thermo-mechanical vibration and buckling analysis of porous FG sandwich plates with geometric discontinuity based on physical neutral surface

The effect of thermo-mechanical load coupling and porosity distributions on vibration and buckling characteristics of Functionally Graded Sandwich Plates (FGSPs) with cutouts is investigated by Finite Element (FE) formulation. Two sandwich configurations are considered and physical neutral surface is incorporated due to material asymmetry. Novel dynamic approach is proposed to evaluate buckling loads. Results obtained are compared with experimental, numerical solutions in literature and revealed that the FGSP buckling capacity under thermomechanical loads improves on using ceramic with lower thermal expansion coefficient. Also, at higher temperature rises, buckling capacity increases due to increasing porosity content, whereas capacity reduces at lower temperature rises.

Influences of bulk structure of Calcarenitic rocks on water storage and transfer in order to assess durability and climate change impact.

The main purpose of this study is to understand influences of bulk structure of geomaterials on water storage and transfer, in order to assess durability and climate change impact on the UNESCO world heritage sites in Alexandria, Egypt. This study deals with the responses of water towards the physiochemical and physicomechanical behaviours of Calcarenitic rocks, that are utilized in Greek and Roman monuments at Alexandria. Many vulnerable archaeological sites [2.3–2.5 m above mean sea level (M.S.L)] are identified at Alexandria, specifically at the Eastern Harbor, El-Shatby the Greek necropolis and Moustafa Kamil Roman tombs and addition to the Roman Catacombs of Kom El-Shoqafa which excavated with deepth − 18 m from the land surface. These UNESCO heritage sites suffer climate change impact (heavy rains and sea water rising) as well as multiple geoenvironmental and geophysical hazards. In this study a general outline of the various tests, surveys and analyses is presented, highlighting the most important issues related to the durability and climate change impact. This paper represents the comprehensive in-situ, field and laboratory surveys and tests undertaken in these outstanding world heritage sites. The field testing program comprises various geotechnical and geophysical field and laboratory tests aiming to define the physical, mechanical and dynamic properties of the hard soils/soft rock materials of the archaeological sites where these outstanding monuments are excavated and constracted. By analysis of linear correlations, some essential mechanisms should be underlined, which may connect the macrostructure to the microstructure of the geomaterial. A systematic method of analysis clearly appeared and emphasized the role of the bulk structure (i.e. grain size, grain contact, specific area, pore shape and microporosity) on petrophysical and petromechanical behavior of rock materials. The study revealed that the petrophysical and geomechanical properties of Calcarenitic rocks are influenced by size, shape, packing of grains, porosity, cement and matrix content, all controlled strongly by depositional fabric and postdepositional processes. The accurate analysis of the physiochemical and physicomechanical behaviours of Calcarenitic rocks that are utilized in Greek and Roman monuments at Alexandria allowed us to define the pathology of these monuments and to estimate the durability, climate change impact and ultimate geostatic loads that they can survive under their present geoenvironmental conditions.

Clinical outcome of CAD/CAM overlays of MIH affected young permanent molars

BackgroundRestoration of first permanent molars with MIH is considered a challenge for dentists because the enamel has less flexibility and hardness with increased porosity and organic content. Materials and methodsThe current study was a randomized control trial in which fifty-two first permanent molars were distributed equally into two groups (Z) teeth that received zirconia overlays and (EC) teeth that received IPS e.max CAD overlays. Clinical assessments were carried out at baseline, 6, and 12 months using modified FDI World Dental Federation criteria. ResultsAfter the observational period of one year, all restorations were still in function with no significant differences in the esthetic, functional, and biological performance of overlays fabricated with zirconia and IPS e.max CAD except one case have been fractured in the group (EC) and three cases have been de-bonding in the group (Z). ConclusionsUsing monolithic zirconia and IPS e.max CAD overlays could be a viable selection for restoring MIH-affected posterior teeth. In further studies, it is advisable to assess the restoration that combines strength with adhesive properties like zirconia-reinforced lithium silicate glass ceramic restoration.

A fuzzy logic based explicit declustering technique

During the spatial estimation of geoscience resource variables, the quantity or quality of minerals and hydrocarbons can be represented by a broad range of properties, including geochemical, geotechnical, or other physical measures. Preferential sampling within the region of interest causes biased global parameters due to clustered sampling patterns. Unbiased sample distribution is essential for conducting conditional simulations to model uncertainty of spatially distributed attributes, e.g. geochemical content of metal or porosity. Therefore, declustering procedures are applied during resource estimation to estimate an unbiased statistical distribution of the measured variables. Traditional techniques such as cell declustering do not consider grade clustering, i.e., the similarity of measured variables within a spatially clustered neighbourhood. This paper presents a declustering technique that explicitly accounts for spatial clustering and the similarity of measured samples' attributes within these spatially clustered samples. In the proposed method, samples were first classified explicitly into spatial and geochemical (grade) clusters using the Fuzzy c-means algorithm. Declustering weights were derived using the Mamdani based Fuzzy Inference System using various T-norm operations. The technique was applied to the publicly available GSLib and Walker Lake datasets. It was shown that the proposed scheme produced more accurate results than those obtained with the traditional declustering technique.